Kinematical structure of the local interstellar medium

Genova, R.; Beckman, J. E.; Álamo, J. Rodríguez

doi:10.1007/bfb0104719

Cited by 2 publications

(1 citation statement)

References 7 publications

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“…Interestingly, the edge of the bubble is only 40 pc in the direction toward PKS 0405À385, suggesting the edge of the local bubble as the site of the ISS screen. In addition, Génova, Beckman, & Alamo (1998) report measurements of Na i absorption lines over a wide range of Galactic longitudes, from which they deduced the kinematics of several local interstellar clouds. They identify an interstellar cloud '' P '' with velocity of 13.8 km s À1 (toward l ¼ 225 , b ¼ 5=4) covering a large solid angle that includes PKS 0405À385.…”

Section: The Local Ismmentioning

confidence: 99%

Interstellar Scintillation of the Polarized Flux Density in Quasar PKS 0405−385

Rickett

Kedziora-Chudczer

Jauncey

2002

ApJ

127

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The remarkable rapid variations in radio flux density and polarization of the quasar PKS 0405À385 observed in 1996 are subject to a correlation analysis, from which characteristic timescales and amplitudes are derived. The variations are interpreted as interstellar scintillations (ISSs). The centimeter wavelength observations are in the weak scintillation regime for which models for the various auto-and crosscorrelations of the Stokes parameters are derived and fitted to the observations. These are well modeled by ISS of a 30 Â 22 las source, with about 180 rotation of the polarization angle along its long dimension. This success in explaining the remarkable intraday variability (IDVs) in polarization confirms that ISS gives rise to the IDV in this quasar. However, the fit requires the scintillations to be occurring much closer to the Earth than expected according to the standard model for the ionized interstellar medium (IISM). Scattering at distances in the range 3-30 pc is required to explain the observations. For our preferred distance of 25 pc the associated source model has a peak brightness temperature near 2 Â 10 13 K, which is about 25 times smaller than previously derived for this source. This reduces the implied Doppler factor in the relativistic jet, presumed responsible to $75, which is still substantially higher than centimeter wavelength VLBI estimates for the Doppler factors in active galactic nuclei (AGNs).

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Section: The Local Ismmentioning

confidence: 99%

Interstellar Scintillation of the Polarized Flux Density in Quasar PKS 0405−385

Rickett

Kedziora-Chudczer

Jauncey

2002

ApJ

127

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Interstellar Scintillation of Pulsar B0809+74

Rickett

Coles

Markkanen³

2000

ApJ

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Weak interstellar scintillations of pulsar B0809+74 were observed at two epochs using a 30m EISCAT antenna at 933 MHz. These have been used to constrain the spectrum, the distribution and the transverse velocity of the scattering plasma with respect to the local standard of rest (LSR). The Kolmogorov power law is a satisfactory model for the electron density spectrum at scales between 2 × 10 7 m and 10 9 m. We compare the observations with model calculations from weak scintillation theory and the known transverse velocities of the pulsar and the Earth. The simplest model is that the scattering is uniformly distributed along the 310 pc line of sight (l = 140 • , b = 32 • ) and is stationary in the LSR. With the scattering measure as the only free parameter, this model fits the data within the errors and a range of about ±10 km s −1 in velocity is also allowed. The integrated level of turbulence is low, being comparable to that found toward PSR B0950+08, and suggests a region of low local turbulence over as much as 90 • in longitude including the galactic anti-center. If, on the other hand, the scattering occurs in a compact region, the observed time scales require a specific velocity-distance relation. In particular, enhanced scattering in a shell at the edge of the local bubble, proposed by Bhat et al. (1998), near 72 pc toward the pulsar, must be moving at about ∼ 17 km s −1 ; however, the low scattering measure argues against a shell of enhanced scattering in this direction. The analysis also excludes scattering in the termination shock of the solar wind or in a nebula associated with the pulsar.

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Kinematical structure of the local interstellar medium

Cited by 2 publications

References 7 publications

Interstellar Scintillation of the Polarized Flux Density in Quasar PKS 0405−385

Interstellar Scintillation of the Polarized Flux Density in Quasar PKS 0405−385

Interstellar Scintillation of Pulsar B0809+74

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